St. Mary’s detectives were trying last month to track a convicted sex offender’s alleged use of Facebook to solicit sexual contact with children, court papers state, when they were told last week that he had raped a 13-year-old girl.

A judge ordered Monday that the Lexington Park man be held in St. Mary’s jail without bond on the new charge of second-degree rape.

A detective notified the FBI earlier this month of complaints that Cameron Antwon Ball, 21, had been seeking out sexual contact with children through the social networking website, court papers state, and the investigator was contacted last Friday about the alleged April 23 incident at an apartment in a Hermanville area neighborhood.

Ball also is accused in charging papers of changing his log-in name on the website without notifying a sex offender registry, and using that new log-in name “to solicit and engage in sexual activity with the victim.”

Capt. Terry Black of the St. Mary’s Bureau of Criminal Investigations said Monday that law officers were closing in on the suspect’s misuse of the website when he switched to a new user name.

“He was surreptitiously creating Internet and log-on ID names in violation of the sex offender registry,” Black said. “He’s supposed to notify us if he does that. He failed to comply.”

The charging papers filed by detective Cpl. William Raddatz allege that Ball had intercourse with the girl and engaged in additional sexual acts with her at the apartment, and he was charged with rape and committing a third-degree sexual offense.